Synthesis and characterization of three novel molybdenum(VI) complexes: Mononuclear [MoO2(C6H4(O)CHNCH(COO)CH2C(O)NH2)], [MoO2(C19H19N2O5)(CH3OH)]Cl · CH3OH and dinuclear [Mo2O4(C6H4(O)CHNCH(COO)CH2C(O)NH2)2]

The molybdenum(VI) complexes [Mo2O4(C6H4(O)CHNCH(COO)CH2CONH2)2] (1), [MoO2(C6H4(O)CHNCH(COO)CH2C(O)NH2)] (3) and [MoO2(C19H19N2O5)(CH3OH)]Cl · CH3OH (4), of salicylaldehyde amino acid derivatives (dl-asparagine or l-ornithine hydrochloride) have been synthesized and characterized. The Schiff base containing a saturated heterocyclic ring (in complex 4) is the first example of such a molecule derived from salicylaldehyde and the amino acid, l-ornithine hydrochloride. We proposed that the formation of a molybdenum(VI) complex coordinated by a Schiff base containing a saturated heterocyclic ring depends upon the nature of the solvent and upon the presence of molybdenum(VI). In the absence of molybdenum(VI), the condensation product obtained from the reaction of l-ornithine hydrochloride and salicylaldehyde was the Schiff base N-salicylidene-l-ornithine (5). In the dinuclear complex 1 and the mononuclear complexes 3 and 4, the molybdenum atoms are octahedrally coordinated with two cis oxo-oxygen atoms (in 3 and 4), oxo-bridging atoms (in 1) and the Schiff base ligand. In 3 the N-salicylidene-dl-asparaginato ligand coordinates molybdenum tetradentately while in 1 and 4 the Schiff base ligand acts as a tridentate ligand.

Graphical abstractThe Schiff base containing a saturated heterocyclic ring is the first example of such a molecule derived from salicylaldehyde and the amino acid, l-ornithine hydrochloride. Our investigation confirmed that the formation of a molybdenum(VI) complex coordinated by the Schiff base containing a saturated heterocyclic ring depends upon the nature of the solvent and upon the presence of molybdenum(VI).Figure optionsDownload full-size imageDownload as PowerPoint slide